Module rail for a photovoltaic system

ABSTRACT

A module rail for a photovoltaic system includes a module-supporting surface extending along the length of the module rail for supporting at least one photovoltaic module thereon. A vertical sidewall extends downward from a side of the module-supporting surface. Fastener openings are spaced apart from one another along the length of the rail. Each of the fastener openings extend through the sidewall generally adjacent to a juncture of the module-supporting surface and the sidewall. Each of the fastener openings is configured to receive a clip fastener for securing a photovoltaic module on the module-supporting surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/310,413, filed Dec. 2, 2011, the entirety of which is hereinincorporated by reference.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a module rail for aphotovoltaic system.

BACKGROUND

A photovoltaic system (or PV system) is a system which uses one or morephotovoltaic modules (or solar panels) to convert sunlight intoelectricity. The system may include multiple components, including thephotovoltaic modules, a racking assembly on which the modules aremounted, mechanical and electrical connections, and devices forregulating and/or modifying the electrical output. Most photovoltaicsystems include a photovoltaic array, which is a linked collection ofphotovoltaic modules. In the case of ground-mounted photovoltaicsystems, the photovoltaic modules are mounted on a plurality of rackingassemblies assembled in vacant land areas. Such ground-mountedphotovoltaic systems may include thousands, if not tens of thousands,photovoltaic modules. Accordingly, the time it takes to assemble eachracking assembly and mount the photovoltaic modules on the rackingassemblies is a significant contributor to the overall cost of thephotovoltaic system. Saving even minutes during assembly of the rackingassembly and during mounting of the photovoltaic modules to the rackingassemblies may significantly reduce the overall cost of the photovoltaicsystem.

SUMMARY

In one aspect, a module rail for a photovoltaic system having a lengthgenerally comprises a module-supporting surface extending along thelength of the module rail for supporting at least one photovoltaicmodule thereon. A vertical sidewall extends downward from a side of themodule-supporting surface. Fastener openings are spaced apart from oneanother along the length of the rail. Each of the fastener openingsextend through the sidewall generally adjacent to a juncture of themodule-supporting surface and the sidewall. Each of the fasteneropenings is configured to receive a clip fastener for securing aphotovoltaic module on the module-supporting surface.

In another aspect, a photovoltaic system generally comprises a modulerail comprising a module-supporting surface extending along the lengthof the module rail, a vertical sidewall extending downward from a sideof the module-supporting surface, and fastener openings spaced apartfrom one another along the length of the rail, each of the fasteneropenings extending through the sidewall generally adjacent to a junctureof the module-supporting surface and the sidewall. At least onephotovoltaic module is secured to the module rail. The photovoltaicmodule includes a lower flange. Clip fasteners secure the at least onephotovoltaic module to the module-supporting surface of the module rail.Each clip fastener includes upper and lower clip jaws partially defininga press-fit channel. The lower clip jaw of each clip fastener isinserted into one of the fastener openings such that themodule-supporting surface and the lower flange of the photovoltaicmodule are press-fit into the press-fit channel.

Other features will be in part apparent and in part pointed outhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of one embodiment of a photovoltaic system, thesystem including a plurality of photovoltaic modules mounted on aracking assembly;

FIG. 2 is a perspective of the racking assembly in FIG. 1, with thephotovoltaic modules removed therefrom, the racking assembly including apair of piers, pier caps secured to the respective piers, and modulerails secured to and extending across the pier caps;

FIG. 3 is an enlarged perspective of one of the photovoltaic modules inFIG. 1;

FIG. 4 is an enlarged, fragmentary cross section of the photovoltaicmodule;

FIG. 5 is a fragmentary left elevational of one embodiment of a pier capsecured to a pier;

FIG. 6 is a fragmentary right elevational of the pier cap and pier inFIG. 5;

FIG. 7 is a fragmentary left elevational of another embodiment of a piercap secured to a pier;

FIG. 8 is a fragmentary right elevational of the pier cap and pier inFIG. 6;

FIG. 9 is an enlarged side elevational view of one of the module railsin FIG. 2;

FIG. 10 is an enlarged, fragmentary top plan view of the module rail;

FIG. 11 is an enlarged, fragmentary front elevational view of the modulerail;

FIG. 12A is an enlarged view taken from FIG. 1, illustrating one of themodule rails secured to one of the pier caps;

FIG. 12B is an enlarged view similar to FIG. 12A, except illustrating asecond embodiment of a rail fastener in an unlocked position;

FIG. 12C is similar to FIG. 12B, except illustrating the rail fastenerin a locked position and tightened to fixedly secure the rail to thepier cap;

FIG. 13 is an enlarged view taken from FIG. 2, illustrating a locatingindication on one of the module rails;

FIG. 14 is an enlarged view taken from FIG. 1, illustrating top-downfastener securing modules to the module rails;

FIG. 15 is an enlarged view taken from FIG. 14, illustrating a firsttop-down fastener securing the modules to the module rails;

FIG. 16 is an enlarged, fragmentary cross section taken through thefirst top down fastener, the modules, and the module rail in FIG. 15;

FIG. 17 is an enlarged view taken from FIG. 14, illustrating a secondtop-down fastener securing a module to the module rail;

FIG. 18 is a cross section taken through the first top down fastener,the module, and the module rail in FIG. 17;

FIG. 19 is a top perspective of a clip fastener;

FIG. 20 a bottom perspective of the clip fastener;

FIG. 21 is a top plan view of the clip fastener;

FIG. 22 is a side elevational view of the clip fastener;

FIG. 23 is an enlarged, fragmentary view of an underside of one of themodules, showing the clip fastener securing the module to the modulerail; and

FIG. 24 is an enlarged, fragmentary cross section taken through themodule, clip fastener, and the rail in FIG. 23.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, and in particular to FIGS. 1 and 2, oneembodiment of a photovoltaic system is generally indicated at referencenumeral 10. The photovoltaic system includes a plurality of photovoltaicmodules (also referred to herein as “modules”), each generally indicatedat 12, mounted on a mounting or racking assembly, generally indicated at14. As explained in more detail below, the racking assembly 14 disclosedherein is a ground racking assembly configured for ground mounting ofthe photovoltaic system 10. It is understood that aspects of thisillustrated embodiment, as disclosed herein below, may be used in arooftop racking assembly configured for mounting the photovoltaic systemon a roof of a building or other structure.

Referring to FIGS. 1 and 3, each module 12 has a generally rectangularperimeter, having a length and a width. The module includes aphotovoltaic cell assembly 16, and a module frame 18 secured to aperimeter of cell assembly. The photovoltaic cell assembly 16 includes aplurality of photovoltaic cells (not shown) electrically connected toone another. In general, the photovoltaic cells are solid stateelectrical devices that convert the energy of light directly intoelectricity by the photovoltaic effect. As is generally known andunderstood, the modules 12 of the photovoltaic system 10 may beelectrically connected to one another to form a photovoltaic array. Theoperation and use of photovoltaic arrays are generally known andunderstood, and beyond the scope of the present disclosure.

Referring to FIGS. 3 and 4, each of the illustrated module frames 18 hasa perimeter sidewall 20, an upper flange 22 extending inward from anupper end of the sidewall, and a lower flange 24 (FIG. 4) extendinginward from a lower end of the sidewall. The upper and lower flanges 22,24, respectively, extend around at least a portion of the perimeter ofthe module frame 18. The photovoltaic cell assembly 16 is securedadjacent the upper flange 22, and the lower flange 24 is spaced belowthe cell assembly. The module frames 18 may be constructed from anelectrically-conductive material, such as aluminum or anotherelectrically conductive metal, having an electrically non-conductiveouter layer disposed over the electrically conductive material. Forexample, the module frames 18 may be constructed from anodized aluminum,which has an outer anodic layer that is electrically non-conductive. Themodule frames may be made from other material, such as other metals, andmay be coated with other types of electrically non-conductive outerlayers, other than anodic layers, or may not have an electricallynon-conductive outer layer. It is understood that photovoltaic modules12 are not presently standardized in the industry, and therefore, theshape, size, and thickness of the anodic layer may vary frommanufacturer to manufacturer. Accordingly, the photovoltaic modules mayhave other configurations without departing from the scope of thepresent invention.

Referring to FIG. 2, the illustrated racking assembly 14 includes firstand second piers 28, 30, respectively, secured to and extending upwardfrom the ground, a pair of spaced apart elongate pier caps, generallyindicated at 32, secured to the respective piers, and a set of modulerails, each generally indicated at 34 (also referred to herein as“rails”), secured to and extending across the pier caps. As explained inmore detail below, the photovoltaic modules 12 are mounted on the modulerails 34 so that the modules lie in a plane that is offset fromhorizontal about 20 degrees to about 30 degrees. As is generally knownin the field of photovoltaic systems, photovoltaic systems in theNorthern Hemisphere are typically arranged so that the photovoltaicmodules face south, while photovoltaic systems in the SouthernHemisphere are typically arranged so that the photovoltaic modules facenorth. Accordingly, in the illustrated embodiment first pier 28 is aneast pier, the second pier 30 is a west pier, the pier caps 28, 30 rungenerally north to south, and the module rails 34 run generally east towest. Hereinafter, for the purpose of describing relative locations ofcomponents and structures, the photovoltaic system 10 described hereinis assumed to be implemented in the Northern Hemisphere. It isunderstood that the photovoltaic system 10 may be assembled in adifferent orientation without departing from the scope of the presentinvention.

The piers 28, 30 of the racking assembly may be of various types havingdifferent shapes and sizes. For purposes of illustrating two types ofpiers, the first pier 28 in the illustrated embodiment is a pipe pierand the second pier 30 is an I-beam pier. It is understood thattypically the racking assembly 14 will include the same type of pier.Regardless of the type or shape of the pier, lower ends of the piers 28,30 are secured to the ground, such as by driving and/or cementing thepiers in the ground, and the pier caps 32 are secured to upper ends ofthe respective piers, as explained in more detail below. In one example,the lengths of the piers 28, 30 are customized and based on a specificapplication. The piers may be constructed from a suitable metal, such assteel (e.g., hot-dip galvanized steel) or aluminum, and may have asuitable load capacity, such as from about 1,000 pounds (4,448 N) toabout 10,000 pounds (44,482 N). It is understood that the piers may beof other shapes and sizes without departing from the scope of thepresent invention. It is also understood that the disclosed rackingassembly may include any number of piers, such as one pier, or more thantwo piers.

In the illustrated embodiment, as shown best in FIGS. 2 and 5-8, each ofthe pier caps 32 comprises an elongate support beam, generally indicatedat 36, having opposite longitudinal ends (e.g., north and south ends), agenerally vertical web with inner and outer web faces 38, 40,respectively, and upper and lower flanges 42, 44, respectively, runningalong the length of the web and extending laterally from adjacentrespective upper and lower sides of the inner web face. As explained indetail below, the upper return flanges 42 are used as a support surfacefor the rails 34, in addition to adding strength to and inhibitingbending of the support beams. The support beams 36 may be formed from asuitable metal, such as steel (e.g., steel with zinc finish) oraluminum, and may be constructed to have a suitable load capacity. Thelengths of the support beams 36 may be customized and may depend on aspecific application. The support beams 36 may be of otherconfigurations, including other shapes, without departing from the scopeof the present invention. It is also understood that the racking 14assembly may not include the pier caps without departing from the scopeof the present invention. For example, the racking assembly 14 mayinclude multiple sets of piers, and each of the module rails 34 may besecured to one of the pier sets by a connector.

Referring to FIGS. 5-8, a pier connection system, generally indicated at50, is provided on each of the pier caps 32 to secure the pier caps tothe respective piers 28, 30. The pier connection system 50 isconfigurable for selectively securing the pier caps 32 to either thepipe pier 28 (FIGS. 7 and 8) or the I-beam pier 30 (FIGS. 5 and 6) sothat the pier caps extend at an angle of about 110 to 120 degreesrelative to the longitudinal axis of the pier (i.e., about 20 to 30degrees relative to horizontal). The pier connection system 50 includesat least one pier cap hanger 52 that engages the upper end of theselected pier 28, 30 to hang the pier cap 32 thereon, and at least onepier clamp (one embodiment indicated by reference numeral 54 in FIGS. 5and 6, and another embodiment indicated by reference numeral 56 in FIGS.7 and 8), disposed below the hanger, for clamping the pier cap on a sideof the pier. Both the pier cap hanger 52 and the pier clamp 54, 56 areused to secure the pier caps to the piers so that the pier caps extenddownward at an angle of about 110 to about 120 degrees relative to thelongitudinal axis of the pier (i.e., about 20 to 30 degrees relative tohorizontal). Moreover, as explained in more detail below when describinga method of assembling the racking assembly 14, the hanger 52 locatesand retains the pier caps 32 at the upper end of the piers 28, 30 priorto tightening the pier clamp 54, 56 to the piers so that the modulerails 34 can be fixedly secured to the pier caps before fixedly securingthe pier caps to the piers. Assembling the racking assembly 14 in thisway facilitates squaring of the racking assembly.

Referring to FIGS. 5 and 6, which shows the pier cap 32 secured to theI-beam pier 30, the pier connection system 50 includes two pier caphangers 52 mounted on the beam 36. The hangers 52 comprise hanger hooks(e.g., J-hooks, indicated by the same reference numeral 52) that arespaced apart from one another along the length of the pier cap. The samehanger hooks 52 can be used to hook onto the respective upper ends ofthe pipe pier 28 and the I-beam pier 30, as shown in FIGS. 5-8. Forexample, bent terminal end margins 58 of the hooks 52 are configured toextend downward into the top opening 60 (FIG. 7) in the upper end of thepipe pie 28, and are configured to engage the central web 62 of theI-beam pier 30 adjacent the upper end of the I-beam pier (FIG. 5). Eachof the hanger hooks 52 is secured to a C-shaped bracket 64 attached tothe support beam 36 of the pier cap 32. A shank 66 of each hanger hook52 extends through aligned shank openings 68 in vertically spaced apartarms 70 of the corresponding C-shaped bracket 64. A nut 72 (broadly, astop) threaded on the shank 66 of the hanger hook 52 inhibits the shankfrom sliding upward, out of the aligned shank openings 68 when thehanger hook is hanging the pier cap 32 on the upper end of the pier 28,30. The vertical positions of the hanger hooks 52 relative to thecorresponding support beam 36 are independently and selectivelyadjustable by adjusting the longitudinal positions of the respectivenuts 72 (or other stops) on the shanks 66, such as by rotating the nutson the threaded shanks to move the nuts upward or downward on the shanksIndependently adjusting the vertical positions of the hanger hooks 52allows for selective adjustment of the angle at which the support beam36 extends with respect to the corresponding pier 28, 30 and withrespect to horizontal. The shank 66 of each hanger hook 52 is alsoselectively and independently rotatable in the corresponding shankopenings 68 about a vertical axis to adjust the horizontal position ofthe terminal end margin 58 of the hanger hook so that the terminal endmargin can hook onto piers of various cross-sectional sizes and shapes.One of the hanger hooks 52 (i.e., the north hook) extends through aclearance slot 74 in the support beam 36 to allow the hook to rotaterelative to the support beam. The other hook 52 (i.e., the south hook)extends above and over the upper return flange 42, and therefore, aclearance slot for this hook is not necessary, although an additionalclearance opening may be provided. The pier cap hangers may be of otherconfigurations without departing from the scope of the presentinvention. Moreover, the pier caps may not include pier cap hangerswithout departing from the scope of the present invention.

Referring to FIGS. 5 and 6, the first embodiment of the pier clamp 54 ofthe pier-rail connection system 50 comprises opposing clamping hooks(e.g., J-hooks, indicated by the same reference numeral 54) that arespaced apart vertically from one another along the length of the supportbeam 36 for attaching the pier cap to the I-beam pier 30. In theillustrated embodiment, two pairs of opposing side hooks may be providedwith the pier cap 32, although only one pair (a lower pair) isillustrated. The clamping hooks 54 hook onto side flanges 78 of theI-beam pier 30 and clamp the pier cap 32 to the side (e.g., inner side)of the I-beam pier, as shown in FIG. 5. Accordingly, the clamping hooks54 are broadly considered to be clamps, and other types of clamps may beused in place of the illustrated clamping hooks without departing fromthe scope of the present invention. Shanks 80 of the clamping hooks 54extend through respective pier-clamp slots 82 in the support beam 36 ofeach pier cap 32, and extend outward from the outer web face 40 of thesupport beam. The pier-clamp slots 82 extend at an angle of about 20 toabout 30 degrees with respect to the length of the support beam 36 sothat the support beam extends at an angle of about 110 to about 120degrees relative to the I-beam pier 30. The shanks 80 of the clampinghooks 54 are selectively and individually slidable along the pier-clampslots 82, when the hooks are not secured to the pier 30, to adjust thehorizontal distance between the clamping hooks and allow for theclamping hooks to accommodate I-beam piers 30 of various widths betweenthe side flanges 78.

When securing the clamping hooks 54 to the I-beam pier 30, the shanks 80run across the respective side flanges 78 of the pier, in contacttherewith, and bent terminal end margins 84 of the respective clampinghooks 54 extend around and engage the respective flanges of the pier.Clamping-hook nuts 86 (broadly, clamping-hook stops) threaded on theshanks 80 of the clamping hooks 54 engage the inner web face 38 of thesupport beam 36. Tightening the clamping-hook nuts 86 on the respectiveclamping hook shanks 80 when the clamping hooks 54 are in engagementwith the I-beam pier 30 inhibits the clamping hooks from withdrawingfrom and moving within the respective pier-clamp slots 82, and firmlyclamps the pier cap 32 to the I-beam pier. Moreover, adjusting theclamping-hook nuts 86 on the respective shanks 80 allows the lengthsclamping hooks 54 extending outward from the outer web face 40 to beselectively and individually adjusted (i.e., increased and decreased).Thus, both the length of the clamping hooks 54 extending outward fromthe outer web face 40 and the spacing between the clamping hooks areselectively adjustable to thereby accommodate I-beam piers 30 (or otherpiers) having various cross-sectional dimensions.

Referring to FIGS. 7 and 8, the second embodiment of the pier clamp 56pier-rail connection system 50 comprises a pipe clamp (indicated by thesame reference numeral 56) for attaching the pier cap 32 to the pipepier 28. The pipe clamp 56 and the clamping hooks 54 are interchangeableand the remaining components of the pier cap 32 for use with the pipepier 28 are the same for use with the I-beam pier. In the illustratedembodiment, two pipe clamps may be provided, although only one clamp 56(a lower clamp) is illustrated. The pipe clamp 56 may be similar to aconventional pipe clamp, such as strut pipe clamp, for securing a pipeto a structure. For example, the illustrated pipe clamp 56 has atwo-piece body. Each body piece 90 is arcuate and elongate, and has atongue 92 at its first end that is insertable into one of the pier-clampslots 82 in the support beam 36 of the pier cap 32 to attach the bodypiece to the support beam. The pier-clamp slots 82 allow for the bodypieces 90 to slide therein to allow for various sized pipe clamps to beattached thereto to accommodate pipe piers 28 of various shapes andsizes. Bent attachment tabs 94 at the opposite ends of the respectivebody pieces 90 have aligned fastener openings for receiving a fastener(e.g., a bolt and nut or a screw; not shown) therethrough to secure thetwo body pieces together and clamp the pier cap 32 to the pipe pier 28.The pier connection system 50 may include other types of fasteners forsecuring the pier caps 32 to the piers 28, 30 without departing from thescope of the present invention.

Referring back to FIGS. 1 and 2, the illustrated racking assembly 14includes four module rails 34: a north rail, a south rail, and twointermediate rails between the north and south rails. The rails 34 arespaced apart in the north-south direction so that each photovoltaicmodule 12 is received between and supported by adjacent rails. In theillustrated embodiment, adjacent rails 34 are spaced apart a suitabledistance from one another to mount the modules 12 in landscapeorientations. As generally known in the field of photovoltaic systems,the photovoltaic modules 12 are in landscape orientations when thelengths of the modules run east to west and the widths of the modulesrun north to south. It is understood that the rails 34 may be configuredfor mounting the modules 12 in portrait orientations, with the lengthsof the modules running north to south and the widths of the modulesrunning east to west.

Referring to FIG. 9, each of the module rails 34 is generally aninverted channel rail having an upper top-hat portion, generallyindicated at 100, opposing sidewalls 102 (e.g., north and southsidewalls) extending downward from opposite respective sides of thetop-hat portion, and lower flanges 104 extending laterally outward fromlower ends of the respective sidewalls. Each module rail may befabricated from a single sheet of suitable metal, such as steel (e.g.,steel with zinc finish) or aluminum, having a suitable gauge, such asfrom about 11 to about 14 gauge. The module rails 34 may be constructedin other ways (e.g., extrusion), and may be of other configurationswithout departing from the scope of the present invention. As explainedin more detail below, the module rails 34 are configured for mountingthe modules 12 thereon using two types of top-down fasteners, generallyindicated at 108, 109, respectively, in FIGS. 15-18, and/or clipfasteners, generally indicated at 110 in FIGS. For purposes ofillustrating and fully disclosing the top-down fasteners 108, 109 andthe clip fasteners 110, only one module 12 in the illustrated embodimentis secured to adjacent rails 34 using the top-down fasteners, and onlyone module is secured to adjacent rails using the clip fasteners. It isenvisioned that in the field all of the modules 12 will be secured tothe rails 34 using either the top-down fasteners 108, 109 or the clipfasteners 110, although it is contemplated that some or all of themodules may be secured to the rails using both types of fasteners.

Referring to FIGS. 9-11, the rail sidewalls 102 and the lower flanges104 provide structural rigidity to the rails 34, to inhibit bending, andprovide a suitable load capacity for the photovoltaic modules 12.Material is removed from the sidewalls 102, forming holes 105 (FIG. 11),to reduce the weight of the module rails 34. The holes 105 may also beused to run cables therethrough. In the illustrated embodiment, thelower flanges 104 are return flanges, which define flange channels. Inone example, the return flanges 104 may be configured to receive cablesfor cable management purposes. Flange openings 106 in the bottoms of thereturn flanges 104, shown best in FIG. 10, allow liquid (e.g., rainand/or melted snow) to flow therethrough to inhibit pooling of liquid inthe flange channels. The flange openings may also be used to runfasteners (e.g., tie fasteners, not shown) therethrough to secure thecables in the flange channels.

As shown best in FIG. 9, the top-hat portion 100 of each rail 34 has anupper, inverted generally U-shaped portion 112 and opposite shoulders114 (e.g., north and south shoulders) extending laterally outward fromopposite lower ends of the inverted U-shaped portion. The top-hatshoulders 114 (broadly, module-supporting surfaces) provide supportsurfaces on which the lower flanges 24 of the module frames 18 aresupported when the modules 12 generally abut the sidewalls of theinverted U-shaped portion. Accordingly, adjacent north and south modules12 are spaced apart from one another, in the north-south direction,generally the width of the inverted U-shaped portion 112. As shown inFIG. 13, a locator 117, such as a bump or other raised structure, isprovided on the shoulders 114 at mid-points along the length of therails 34. The locator 117 allows a user to locate the middle modules 12on the racking assembly 14, as explained below when disclosing a methodof assembling the photovoltaic system 10.

As shown best in FIGS. 10 and 12A, a plurality of top-down fasteneropenings 116 (broadly, a first set of openings) extend through a top 118(broadly, an upper portion of the rail) of the inverted U-shaped portionof the top-hat portion 100. The inverted U-shaped portion also hasopposing sides extending downward from opposite sides of the top 118. Asexplained in more detail below, the top-down fastener openings 116 areused for attaching the top-down fasteners 108, 109 to the rail 34 tosecure the modules 12 to the rail. The top-down fastener openings 116are spaced apart from one another along the length of the module rail adistance D1, which may measure from about ⅜ in (about 9.5 mm) to about1.5 in (about 38.1 mm). Referring to FIGS. 10 and 11, each module rail34 also has a plurality of clip fastener openings 122 (broadly, a secondset of openings) generally adjacent to the junctures of the shoulders114 and the respective sidewalls 102 of the rail. In the illustratedembodiment, each clip fastener opening 122 extends through portions ofboth the corresponding shoulder 114 and the sidewall 102, although theclip fastener openings may extend through one or the other of theshoulder and the sidewall. As explained in more detail below, the clipfastener openings 122 are configured to receive the clip fasteners 110for securing the modules 12 to the module rails 34. The clip fasteneropenings 122 are generally slot-shaped, each having a length L1extending along the length of the module rail 34, and width W1 extendingfrom the shoulder 114 to the sidewall 102 of the rail 34. In oneexample, the length L1 of each clip fastener opening 122 may be fromabout 1.5 in (about 38.1 mm) to about 3.0 in (about 76.2 mm). Adjacentclip fastener openings 122 are spaced apart from one another a distanceD2, measuring from about 8.0 in (about 20.3 cm) to about 12.0 in (about30.5 cm). The clip fastener openings 122 may have other shapes and sizesand other locations without departing from the scope of the presentinvention. Moreover, the rails 34 may not include the clip fasteneropenings 122 without departing from the scope of the present invention.

Referring to FIG. 12A, in one embodiment the module rails 34 have railfastener openings 124 in lower flanges 104 (broadly, in lower portionsof the rails) that receive rail fasteners 126 on the respective piercaps 32 to secure the rails to the pier caps. In the illustratedembodiment, each rail fastener 126 is a thread cutting screw (only ahead of the screw is visible in FIG. 12A, and is indicated by the samereference numeral 126) secured to the upper return flange 42 (broadly,rail support portion) of the pier cap 32. An upper portion of the threadcutting screw 126 extends above the upper return flange 42 so that thehead of the screw and a portion of a shaft (not shown) are disposedabove the upper return flange 42. Each rail fastener opening 124 has akeyhole shape for receiving the head of the screw 126 and the uppershaft portion therethrough. In particular, each rail fastener opening124 has an enlarged clearance portion 130 having dimensions greater thandimensions of the head of the screw 126 so that the head can be insertedfrom below the rail up through the clearance portion. Each rail fasteneropening 124 also has narrower slot-shaped portion 132 having a widthless than the width of the head of the screw 126 and greater than thewidth of the upper shaft portion for inhibiting the head fromwithdrawing from the slot-shaped portion while allowing the shaft of thescrew to slide along the slot-shaped portion. To secure the rail 34 tothe pier caps 32, the rail is positioned on the upper return flanges 42of the pier caps such that the head of the screws 126 on the pier capsextend through the clearance portions 130 of the respective railfastener openings 124. The rail 34 is then slid across the pier caps 32in the east-west direction so that the upper portions of the screwshafts enter the slot-shaped portions 132 of the respective railfastener openings 124. The rail 34 is slid in the east-west directionuntil the screw shafts abut the rail at the opposite ends of theslot-shaped portions 132 of the rail fastener openings 124. The threadcutting screw 126 are then tightened down to firmly secure the rails 34to the pier caps 32.

The module rails may be secured to the pier caps in other ways.Referring to FIGS. 12B-12C, in one non-limiting example, the railfastener, generally indicated at 136, is a twist lock fastener having anelongate channel nut 138 (broadly, a locking member) threaded on a shaftof a bolt 139 extending through a through hole in the upper returnflange 42 (a head of the bolt—not shown—engages an underside of theupper return flange). The channel nut 138 is positionable between anunlocked position (FIG. 12B), in which the channel nut is insertable upthrough the rail fastener opening 140 from below and rotatable withinthe flange channel defined by the return flange 104, and a lockedposition, in which the channel nut is rotated a quarter turn from itsunlocked position such that the channel nut extends cross-wise (i.e.,generally transverse) with respect to the rail fastener opening 140 andthe flange channel. When the channel nut 138 is in its locked position,it is inhibited from withdrawing from the fastener opening 140 andinhibited from further rotation (e.g., beyond a quarter turn) withrespect to the flange 104, whereby the bolt 139 can be rotated from theunderside of the flange 104 to tighten the channel nut on the rail 34and secure the rail to the pier cap 32. In the illustrated embodiment,the channel nut 138 has opposite longitudinal ends each havingdiagonally opposite corners that are rounded or radiused to allow thefastener head to rotate a quarter turn within the channel flange, anddiagonally opposite corners that engage the sidewall 102 and the returnportion of the flange 104 (each of which define respective sides of theflange channel) to inhibit further rotation of the channel nut. The railfastener 136 includes a spring 141 that urges the channel nut 138 andthe bolt 139 upward relative to the upper flange 42 of the pier cap 32so that the fastener head is received in the flange channel and abovethe bottom of the channel.

As disclosed above, the illustrated module rails 34 allow thephotovoltaic modules 12 to be mounted thereon using the top-downfasteners 108, 109. In one embodiment, as shown in FIGS. 14-18, thefirst top-down fastener 108 is configured for mounting adjacent northand south modules 12 to a common rail 34, and the second top-downfastener 109 is configured for mounting north-end modules and south-endmodules to the respective north and south rails. It is contemplated thatracking assembly 14 may include a single, universal top-down fastener(not shown) for mounting all of the modules to the rails.

Referring to FIGS. 15 and 16, the illustrated first top-down fastener108 includes a body, generally indicated at 150, having a centralU-shaped portion 152 sized and shaped to fit within space definedbetween the adjacent north and south modules 12 when the modules areresting on the shoulders 114 of the adjacent north and south rails 34.Opposite north and south engagement flanges 154 of the body 150 extendsoutward from opposite sides of the central U-shaped portion 152. Aconnector opening 156 in a base of the U-shaped portion 152 of the bodyis alignable with a single one of the top-down fastener openings 116 inthe rail 34. A thread cutting screw 158 (broadly, a connector) of thetop-down fastener 108 is insertable through the connector opening 156 inthe U-shaped portion 152 and threaded through the aligned top-downfastener opening 116, which functions as a pilot hole for the threadcutting screw. In another embodiment, the top-down fastener may includea bolt and a nut, or other type of connector, instead of the threadcutting screw 158. The engagement flanges 154 on opposite north andsouth sides of the U-shaped portion 152 engage the upper flanges 22 ofthe respective module frames 18. Upon tightening of the screw 158 on therail 34, the engagement flanges 154 clamp down on the respective northand south module frames 18 to hold the modules in place on the shoulders114 of the rail 34. The body 150 of the illustrated first top-downfastener 108 includes ribs 162 extending between the opposite engagementflanges 154, and across the U-shaped portion 152, to provide structuralrigidity to the body and inhibit bending of the body as the screw 158 istightened and as the engagement flanges clamp down on the modules 12.The top-down fastener may be of other configurations, or the rackingassembly 14 may not include the top-down fasteners, without departingfrom the scope of the present invention.

As set forth above, the second top-down fastener 109 is configured formounting north-end modules 12 and south-end modules to the respectivenorth and south rails 34. Referring to FIGS. 17 and 18, the illustratedembodiment of the second top-down fastener 109 includes a body,generally indicated at 166, having a generally inverted L-shape. Thebody 166 has a central portion 168, a leg 170 extending downward from afirst side of the central portion, and an engagement flange 172extending upward and laterally outward from an opposite second side ofthe central portion. The second top-down fastener 109 is configured suchthat the engagement flange 172 engages the upper flange 22 of the moduleframe 18, and the leg 170 extends downward into the clip fasteneropening 122 in the north (or south) rail 34. A connector opening 174 inthe central portion 168 of the body 166 is aligned with a single one ofthe top-down fastener openings 116 in the rail 34. A thread cuttingscrew 176 (broadly, a connector) of the second top-down fastener 109 isinsertable through the connector opening 174 in the central portion 168and threaded into the aligned top-down fastener opening 116, whichfunctions as a pilot hole for the thread cutting screw. In anotherembodiment, the top-down fastener may include a bolt and a nut, or othertype of connector, instead of the thread cutting screw 176. Upontightening the screw 176, the engagement flange 172 clamps down on theupper flange 22 of the module 12 to hold the module on the shoulder 114of the rail 24. The depending leg 170, which is received in an alignedclip fastener opening 122, inhibits the second top-down fastener 109from rotating relative to the rail 34 so that the engagement flange 172is retained in engagement with the upper flange 22 of the module frame18 as it is clamped down. The illustrated body 166 of the secondtop-down fastener 109 includes ribs 180 extending across the centralportion 168 of the body to the engagement flange 172 to providestructural rigidity to the body and inhibit bending of the body as thescrew 176 is tightened and as the engagement flange clamps down on themodule 12. The second top-down fastener may be of other configurations,or the racking assembly 14 may not include the second top-downfasteners, without departing from the scope of the present invention.

In addition to clamping the modules 12 on the rails 34, in theillustrated embodiment the first and second top-down fasteners 108, 109,respectively, are configured to provide an electrical connection betweenthe modules and the rails to facilitate electrically grounding of themodules. As described above, the module frames 18 have an outer,electrically non-conductive anodic layer covering the electricallyconductive material (e.g., aluminum). To facilitate an electricalconnection, each engagement flange 154, 172 of the first and secondtop-down fasteners 108, 109, respectively, includes one or more piercingmembers 184 that pierce (e.g., score, scrape, dig, and/or puncture)through the anodic, or other non-conductive outer layer, and makeelectrical contact with the electrically conductive material (e.g.,aluminum) as the respective top-down fastener is clamped down. In theillustrated embodiment (FIGS. 15-18), the piercing members 184 compriseteeth (indicated by the same reference numeral 184) formed on (e.g., atthe corners of) the respective engagement portions 154, 172. By way ofexample only, the teeth 184 are formed by bending the corners of therespective engagement portions 154, 172 slightly downward, at an angleless than about 30 degrees, such as from about 1 degree to about 10degrees (e.g., 8 degrees), relative to the engagement flange. As thetop-down fastener 108, 109 is clamped down by tightening thecorresponding screw 158, 176, the teeth 184 contact the module frame(s)18 and scrape or score (i.e., puncture) the anodic layer. Furtherclamping of the engagement flange(s) 154, 172 on the frame(s) 18 causesthe teeth 184 to resiliently deflect upward slightly (i.e., flatten out)relative to the engagement flange(s), whereby the teeth continue toscore the anodic layer, while being urged into contact with theelectrically-conductive material, to increase the area of contactbetween the teeth and the electrically-conductive material. It isunderstood that the teeth or other piercing member may be formed inother ways and may be of other configurations without departing from thescope of the present invention.

In the embodiment where both of the top-down fasteners 108, 109 areconfigured for grounding, each fastener, including the teeth 184 and thescrews 158, 176 thereof, are electrically conductive so as to define anelectrical path from the electrically-conductive material of the moduleframes 18 to the rails 34, which are electrically grounded. The top-downfasteners 108, 109 are capable of electrically conducting current asrequired by UL 467 and/or UL2703, to effectively ground the modules 12through the rails 34. In one non-limiting example, the top-downfasteners 108, 109 are constructed to have a current-carrying capacityof at least 750 amps for four seconds to satisfy the requirement of UL467. In another non-limiting example, the top-down fasteners 108, 109may be wired in series with an applicable fuse (e.g., a 60 amp fuse) andconnected to a 5,000 amp source. In this example, the top-down fasteners108, 109 have a current-carrying capacity of at least 135% current(e.g., 81 amperes, where the fuse is a 60 am fuse) for sixty minutes andat least 200% current (e.g., 120 amperes, where the fuse is a 60 amfuse) for four minutes. It is understood that the top-down fasteners108, 109 may have other current-carrying capacities without departingfrom the scope of the present invention. Each of the first and secondtop-down fasteners 108, 109 may be fabricated from a single sheet ofmetal, such as stainless steel (e.g., heat treated stainless steel) orsteel having an electrically conductive and anti-corrosive coating, suchas a zinc coating. Other ways of constructed the first and secondtop-down fasteners 108, 109 do not depart from the scope of the presentinvention. It is understood that only one of the first and secondtop-down fasteners 108, 109, or neither of the first and second top-downfasteners, may be capable of piercing the anodic layer, or otherelectrically non-conductive outer layer, of the module frames 18 tofacilitate grounding of the modules 12.

Referring to FIGS. 19-24, the clip fasteners 110 are configured forunderside mounting of the modules 12 to the rails 34, as shown best inFIGS. 23 and 24. As disclosed above, the shoulders 114 (broadly, modulesupport portions) of the rails 34 are configured to support at leastportions of the lower flanges 24 of the module frames 18. Theillustrated clip fasteners 110 are configured for securing (e.g.,clipping or clamping) the modules 12 on the shoulders 114 of the modulerails 34. In particular, each clip fastener 110 defines a press-fitchannel 190 in which the lower flange 24 of the module frame 18 and theshoulder 114 of the module rail 34 are press fit (FIGS. 23 and 24) tosecure the module 12 to the rail 34. The illustrated clip fastener 110includes a channel base (or loop) 192 and opposing upper and lower clipjaws 194, 196 (broadly, first and second clip jaws) extending from thechannel base 192 to define the press-fit channel 190. It is understoodthat one or both of the upper and lower clip jaws 194, 196, as with theillustrated embodiment, may have openings therethrough, whereby thepress-fit channel 190 is discontinuous across the clip fastener 110. Theclip fastener 110 is configured to be pressed on the lower flange 24 andthe shoulder 114 so that the upper clip jaw 194 engages the lower flange24 of the module frame 18, and the lower clip jaw 196 extends through aselected one of the clip fastener openings 122 in the rail 34 andengages the underside of the shoulder 114. This clip fastener may bereferred to as a “hammer-on” fastener, although a hammer is notnecessarily used to press the clip 110 on the lower flange 24 and theshoulder 114.

In the illustrated embodiment, each clip fastener 110 is a spring clipfastener, whereby at least one of upper and lower clip jaws 194, 196 isresiliently deflectable away from the other clip jaw as the fastener ispressed on the lower flange 24 and the shoulder 114. The illustratedclip fastener 110 includes ribs 198 extending along the fastener fromthe upper clip jaw 194 to the lower clip jaw 196 to provide structuralrigidity to the clip jaws and inhibit bending, and to increase thespring force exerted by the spring clip. In the illustrated embodiment,the clip jaws 194, 196 extend toward one another from the channel base192 such that the channel base and the clip jaws have a generallytriangular or tapered profile. A throat 200 of the press-fit channel 190is defined generally at the apex of the triangular or tapered profile(i.e., the location where the clip jaws are the least distance apartfrom one another). The upper clip jaw 194 is resiliently deflectableabout an upper bend line L1 adjacent the juncture of the channel base192 and the upper clip jaw, and the lower clip jaw 196 is resilientlydeflectable about a lower bend line L2 adjacent the juncture between thechannel base and the lower clip jaw. When the clip fastener 110 issecured to the lower flange 24 and the shoulder 114 (FIGS. 23 and 24),tension at the bend lines L1, L2 urges the clip jaws 194, 196 toward thelower flange 24 and the shoulder 114, thereby squeezing or compressingtogether the lower flange and the shoulder to firmly secure the module12 to the rail 34. Terminal end margins 202, 204 (or lips) of therespective upper and lower clip jaws 194, 196 flare outward, atlocations adjacent to the throat 200, to define an enlarged entrance 206of the press-fit channel 190 that facilitates insertion of the lowerflange 24 and the shoulder 114 into the press-fit channel. The clipfastener 110 may be of other configurations without departing from thescope of the present invention.

In one embodiment, the clip fasteners 110 are configured to resist liftproduced by wind forces acting on the modules 12. The clip fasteners 110may be configured to resist lift forces that are from about 25 lbs/ft²(1197 N/m²) to about 30 lbs/ft² (1436 N/m²) or as much as 50 lbs/ft²(2394 N/m²) to about 70 lbs/ft² (3352 N/m²). In one example, the modules12 may be 18 ft² (1.7 m²), and four clip fasteners 110 may be used tosecure each of the modules to the rails 34. Thus, where the photovoltaicsystem 10 is rated to resist lift forces of 30 lbs/ft² (1436 N/m²), eachclip fasteners 110 may be configured to hold at least about 135 lbs (601N). Thus, for each clip fastener 110 an install deflection of the clipfastener multiplied by a spring constant of the clip fastener must begreater than or equal to 135 lbs (601 N). In one example, the distancebetween the jaws 194, 196 at the throat 200 of each clip fastener 110 isabout 0.070 in (0.18 cm). The thinnest stack of material the clipfastener may be installed on may be fourteen gauge steel (East-WestRail) with a 0.080 in (0.20 cm) thick solar module flange on it. Thus,the clamp will open at least an additional 0.080 in (0.20 cm), i.e., thejaws 194, 196 will deflect at least a distance of about 0.080 in (0.20cm), when installed. So, the clip fastener 110 may have a suitableminimum spring constant of about 135 lbs/0.080 in (601 N/0.20 cm) orabout 1688 lb/in (191 N/m). It is envisioned that the clip fasteners mayhave a minimum spring constant of from about 1400 lb/in (158 N/m) toabout 2000 lb/in (226 N/m), preferably from about 1500 lb/in (169 N/m)to about 1900 lb/in (215 N/m). The clip fastener 110 may be constructedto have a spring constant other than set forth above without departingfrom the scope of the present invention.

The illustrated clip fastener 110 includes a depth stop 210 andwithdrawal stop 212 on the lower clip jaw 196. The depth stop 210 andthe withdrawal stop 212 facilitate proper positioning and retention ofthe clip fastener 110 on the lower flange 24 and the shoulder 114. Inparticular, once the clip fastener 110 is properly positioned on thelower flange 24 and the shoulder 114, as shown in FIGS. 23 and 24, theillustrated depth stop 210 inhibits further advancement of the clipfastener relative to the lower flange 24 and the shoulder 114, and thewithdrawal stop 212 inhibits withdrawal of the clip fastener away fromthe lower flange and the shoulder. In the illustrated embodiment, thedepth stop 210 and the withdrawal stop 212 facilitate positioning of theclip fastener 110 such that upper clip jaw 194 engages a portion of thelower flange 24 that extends past the shoulder 114, and only theterminal end margin 204 of the lower clip jaw 196 engages underside ofthe shoulder 114. As shown in FIG. 24, the teeth 220 engage the lowerflange 24 at a location that is directly above the lower clip opening122.

This position of the clip fastener 110 will be attained regardless ofthe size and shape of the lower flange 24, as long as the longer flangehas a length that is not greater than the depth of the press-fit channel190.

The illustrated depth stop 210 is generally in the form of a tab anglingdownward from the lower clip jaw 196 away from to the channel base 192and generally toward the throat 200. A terminal end 214 of the depthstop 210 is located a suitable distance below the lower clip jaw 196such that, in use, the terminal end of the tab contacts the exteriorsurface of rail sidewall 102 below the corresponding clip fasteneropening 122. Thus, the depth stop 210 is configured to restrict theamount the lower clip jaw 196 is insertable into the clip fasteneropening 122 by being configured to contact the rail sidewall 102 andinhibits further advancement of the clip fastener 110 relative to thelower flange 24 and the shoulder 114 when the clip fastener is properlylocated on the shoulder and the lower flange. In this way, the depthstop 210 facilitates proper placement of clip fastener 110, independentof the length of the lower flange, and without having to estimate orotherwise determine whether the clip fastener is properly securing themodule 12 to the rail 34. Other ways of properly positioning the clipfastener 110 on the lower flange 24 and shoulder 114 do not depart fromthe scope of the present invention. Moreover, the clip fastener 110 maynot include a depth stop without departing from the scope of the presentinvention.

The withdrawal stop 212 is generally in the form of a tab anglingdownward from adjacent the terminal end margin 204 of the lower clip jaw196 and generally toward the throat 200. A terminal end 216 of thewithdrawal stop 212 is located a suitable distance below the lower clipjaw 196 such that when the clip fastener 110 is properly securing themodule 12 to the rail 34, the terminal end of the withdrawal stop isadjacent to the interior surface 218 of the rail sidewall 102 below theclip fastener opening 122, and the terminal end of the withdrawal stopcontacts the interior surface when attempting to withdrawal the lowerclip jaw from the clip fastener opening. When pressing on the clipfastener 110, such as by hammering on, the lower clip jaw 196 enters theclip fastener opening 122 in the rail 34, and the withdrawal stop 212resiliently deflects toward the lower clip jaw 196 and enters the clipfastener opening 122. After the terminal end 216 of the withdrawal stop212 passes through the clip fastener opening 122, the withdrawal stoprebounds to its original configuration to inhibit unintentionaldisengagement of the clip fastener 110 from the lower flange 24 and therail 34. It is envisioned that a tool, such as a screw driver, may beused to resiliently deflect the withdrawal stop 212 toward the lowerclip jaw 196 so that the lower clip jaw 196 may be withdrawn from theclip fastener opening 122.

In addition to securing the modules 12 on the rails 34, the illustratedspring clip fastener 110 is configured to provide an electricalconnection between the modules and the rails to facilitate grounding ofthe modules. It is understood that in at least one embodiment the clipfastener may not be capable of providing an electrical connectionbetween the modules and the rails, but instead, the clip fastener isused solely to secure the modules to the rails. Also, in at least oneother embodiment, the clip fastener may not be capable of adequatelysecuring the modules to the rails, but instead the clip fastener may beused solely for the purpose of electrically connected the module to theracking system to ground the module.

As set forth above, the module frames 18 have a electricallynon-conductive anodic layer covering the electrically conductivematerial. Accordingly, the upper clip jaw 194 of the spring clipfastener 110 includes one or more piercing members 220 that piercethrough (e.g., score, scrape, dig, and/or puncture) the anodic layer, orother electrically non-conductive outer layer, and make electricalcontact with the electrically conductive material (e.g., aluminum) asthe lower flange 24 of the module frame 18 is press-fit in the press-fitchannel 190. In the illustrated embodiment, the piercing members 220comprise teeth (indicated by the same reference numeral 220) formedadjacent opposite sides of the upper clip jaw 194 and at intermediatelocations between the opposite sides. The teeth 220 extend slightlydownward from the terminal end margin 202 of the upper clip jaw 202 andinto, or generally adjacent to, the throat 200 of the press-fit channel190. It is understood that the teeth 220 may extend into another portionof the press-fit channel 190 other than the throat 200. The teeth 220may extend at an angle from about 15 degrees to about 45 degreesrelative to the terminal end margin 202 of the upper clip jaw 194. Asthe clip fastener 100 is pressed on, hammered on, or otherwise press fiton the lower flange 24 and the rail 34, the teeth 220 engage the lowerflange 24 and score or scrap (i.e., puncture) the anodic layer andcontact the electrically-conductive material. Initially, the teeth 220may extend at an angle from about 30 degrees to about 60 degrees,preferably about 45 degrees, relative to the upper surface of theshoulder 114 such that the teeth dig or plow through the anodized layeron the lower flange 24. Further press fitting of the clip fastener 110on the lower flange 24 may cause the teeth 220 to resiliently deflectupward (i.e., flatten out) relative to the terminal end margin 202 ofthe upper clip jaw 194, whereby the teeth continue to score the anodizedlayer, while being urged into contact with the electrically-conductivematerial, to increase the area of contact between the teeth and theelectrically-conductive material.

The clip fasteners 110, including the teeth 220, are electricallyconductive so as to define an electrical path from theelectrically-conductive material of the module frames 18 to the modulesrails 34, which are grounded. The clip fasteners 110 are capable ofelectrically conducting current as required by UL 467 and/or UL2703, toeffectively ground the modules through the rails. In particular, theclip fasteners 110 have a current-carrying capacity of at least 750 ampsfor four seconds. In one non-limiting example, the clip fasteners 110are constructed to have a current-carrying capacity of at least 750 ampsfor four seconds to satisfy the requirement of UL 467. In anothernon-limiting example, the clip fasteners 110 may be wired in series withan applicable fuse (e.g., a 60 amp fuse) and connected to a 5,000 ampsource. In this example, the clip fasteners 110 have a current-carryingcapacity of at least 135% current (e.g., 81 amperes, where the fuse is a60 am fuse) for sixty minutes and at least 200% current (e.g., 120amperes, where the fuse is a 60 am fuse) for four minutes. It isunderstood that the clip fasteners 110 may have other current-carryingcapacities without departing from the scope of the present invention.The clip fasteners 110 may be fabricated from a single sheet of metal,such as spring steel. In such an embodiment, the single sheet of metalmay be bent to form the upper and lower clip jaws 194, 196,respectively, and the sheet may be lanced to form the depth andwithdrawal stops 210, 212, respectively, and the teeth 220. Other waysof making the first and second top-down fasteners do not depart from thescope of the present invention.

In one embodiment of a method of assembling the photovoltaic system 10illustrated in FIG. 1, the piers 28, 30 are secured in the ground, suchas by cement or by driving the piers into the ground. Next, thepre-assembled pier caps 32, each of which includes the hanger hooks 52and the pier clamp(s) 54, 56, are placed on the piers 28, 30 by hangingthe hanger hooks on the upper ends of the respective piers. In oneexample, the pier clamp(s) 54, 56 can be loosened and slid downward overthe upper end of the pier 28, 30 until the upper hanger hooks 52 engagethe upper end of the pier. In another example, the pier clamp(s) 54, 56can be loosened and/or positioned so that the hanger hooks 52 engage theupper end of the pier 28, 30 without the pier clamp(s) engaging thepier, and then the pier clamp(s) can be positioned to loosely engage thepier.

With the pier caps 32 hanging on (i.e., loosely engaging) the piers 28,30, each module rail 34 is individually secured to the pier caps. In oneexample, the rails 34 are secured to the pier caps 32 by placing eachrail on the upper flanges 42 of the pier caps so that the respectiverail fasteners 126 on the pier caps enter the clearance portions 130 ofthe respective rail fastener openings 124 in the rail 34. With the railfasteners 126 in the respective clearance portions 130, the rail 34 isslid across the piers caps 32 until the rail fasteners engage the railat the end of the slot-shaped portions 132 of the rail fastener openings124. The rail fasteners 126 are then tightened to firmly secure the rail34 to the pier caps 32. In the example where the rail fasteners aretwist locks 136, the twist lock heads 138 are inserted into the railfastener openings 140, and then rotated from their unlocked positions totheir locked positions to firmly secure the rail to the pier caps.

After firmly securing all of the rails 34 to the pier caps 32, the piercaps can be firmly secured to the piers 28, 30, such as by tighteningthe pier clamp(s) 54, 56 on the respective piers. This method of firstloosely securing the pier caps 32 to the piers 28, 30 and then firmlysecuring the pier caps to the piers after firmly securing all of therails 34 to the pier caps, quickly and easily squares the rackingassembly 14 without having to take measurements and perform additionalsquaring procedures. Moreover, it is envisioned that a two-person teamcan quickly and easily assembly the racking assembly 14 using thismethod.

After assembling the racking assembly 14, the photovoltaic modules 12are secured to the rails 34 using the top-down fasteners 108, 109 and/orthe clip fasteners 110. It is envisioned that the two middle modules 12will be secured to rails using the locator 117 on the intermediate rails34. For example, the west side of the east, middle module 12 and theeast side of the west, middle module may be placed in abutting relationwith the locating bumps 117 on the shoulders 114 of the rails 34. Next,the person(s) assembling will secure modules 12 to the north and southof the two middle modules, and the modules at the east and west endswill be secured last. The modules 12 may be secured to the rails in adifferent order without departing from the scope of the presentinvention. The top-down fasteners 108, 109 and/or the clip fasteners 110are secured to the module frames 18 generally at the quarter-points ofeach module 12. Each module has four quarter-points: two north quarterpoints, and two south quarter points. The quarter-points are located atone-quarter (¼) of the length of the module, and three-quarters (¾) ofthe length of the module.

It is envisioned that securing the modules 12 to the rails 34 using theclip fasteners 110 will be the preferred choice by the person(s)assembling the racking assembly 14, as the use of the clip fastenersrequires less tools, includes less individual components, and is lesslabor-intensive than the top-down fasteners 108, 109. However, somecommercial photovoltaic modules 12 presently on the market do notinclude a frame 18 with lower flange 24, and therefore, it is notpossible to secure these modules using the illustrated clip fasteners110. Accordingly, in situations where the module frames 12 do notinclude lower flanges 24, the person(s) assembling the photovoltaicsystem 10 may use the top-down fasteners 108, 109.

Having described embodiments of the invention in detail, it will beapparent that modifications and variations are possible withoutdeparting from the scope of the invention defined in the appendedclaims.

When introducing elements of the present invention or the preferredembodiments(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions, products,and methods without departing from the scope of the invention, it isintended that all matter contained in the above description and shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:
 1. A module rail for a photovoltaic system, themodule rail having a length and comprising: a module-supporting surfaceextending along the length of the module rail for supporting at leastone photovoltaic module thereon; a vertical sidewall extending downwardfrom a side of the module-supporting surface; and fastener openingsspaced apart from one another along the length of the rail, each of thefastener openings extending through the sidewall generally adjacent to ajuncture of the module-supporting surface and the sidewall, wherein eachof the fastener openings is configured to receive a clip fastener forsecuring a photovoltaic module on the module-supporting surface.
 2. Themodule rail set forth in claim 1, wherein each of the fastener openingsalso extends through the module supporting portion.
 3. The module railset forth in claim 1, wherein each of the fastener openings isslot-shaped.
 4. The module rail set forth in claim 1, further comprisingan upper portion extending upward from the module-supporting surface. 5.The module rail set forth in claim 4, further comprising anothermodule-supporting surface extending along the length of the module railfor supporting at least one photovoltaic module thereon, wherein themodule-supporting surfaces are at opposite sides of the upper portion.6. The module rail set forth in claim 5, further comprising anothervertical sidewall extending downward from a side of the othermodule-supporting surface, wherein the vertical sidewalls generallyoppose one another.
 7. The module rail set forth in claim 6, furthercomprising lower flanges extending laterally outward from lower ends ofthe respective sidewalls.
 8. The module rail set forth in claim 1, incombination with a plurality of clip fasteners for securing the at leastone photovoltaic module to the module rail, each of the clip fastenersincludes upper and lower clip jaws partially defining a press-fitchannel, wherein the lower clip jaw is sized and shape for insertioninto any one of the fastener openings.
 9. A photovoltaic systemcomprising: a module rail comprising a module-supporting surfaceextending along the length of the module rail, a vertical sidewallextending downward from a side of the module-supporting surface, andfastener openings spaced apart from one another along the length of therail, each of the fastener openings extending through the sidewallgenerally adjacent to a juncture of the module-supporting surface andthe sidewall; at least one photovoltaic module secured to the modulerail, the photovoltaic module including a lower flange; and clipfasteners securing the at least one photovoltaic module to themodule-supporting surface of the module rail, each clip fastenerincluding upper and lower clip jaws partially defining a press-fitchannel, wherein the lower clip jaw of each clip fastener is insertedinto one of the fastener openings such that the module-supportingsurface and the lower flange of the photovoltaic module are press-fitinto the press-fit channel.
 10. The photovoltaic system set forth inclaim 9, wherein each of the fastener openings also extends through themodule-supporting surface.
 11. The photovoltaic system set forth inclaim 9, further comprising an upper portion extending upward from themodule-supporting surface.
 12. The photovoltaic system set forth inclaim 11, further comprising another module-supporting surface extendingalong the length of the module rail, wherein the module-supportingsurfaces are at opposite sides of the upper portion.
 13. Thephotovoltaic system set forth in claim 12, further comprising anothervertical sidewall extending downward from a side of the othermodule-supporting surface, wherein the vertical sidewalls generallyoppose one another.
 14. The photovoltaic system set forth in claim 13,further comprising lower flanges extending laterally outward from lowerends of the respective sidewalls.
 15. The photovoltaic system set forthin claim 14, wherein each of the fastener openings is slot-shaped.